Controlled-release fastening device

Abstract

A controlled-release fastening device including a toothed strap with pitched toothing, a base on which is mounted at least one main hook pivotal with respect to the base between a retaining position, in which the hook is selectively engaged between contiguous teeth of the toothing in order to hold the strap in one direction with respect to the base, and a release position, in which at least one hook is disengaged from the strap, allowing the sliding thereof relative to the base. A ratchet is mounted on the base for the gradual release of the strap by one or more teeth at a time. The ratchet including a first and a second hook mutually spaced by a non-integral multiple of the toothing pitch and capable of alternately engaging the toothing during controlled release of the strap. The first hook of the escapement ratchet mechanism coincides with the main hook and the second hook is structurally independent of the first hook, hinged on the base coaxially with the first hook and operationally connected to the first hook in order to disengage it from the toothing of the strap when the second hook is engaged therein and vice versa.

1. A controlled-release fastening device comprising: a toothed strap with pitched toothing, a base on which is mounted at least one main hook pivotal with respect to the base between a retaining position, in which the hook is selectively engaged between contiguous teeth of the toothing in order to hold the strap in one direction with respect to the base, and a release position in which said at least one hook is disengaged from the strap, allowing the sliding thereof relative to the base, a ratchet, comprising an escapement ratchet mechanism, being mounted on the base for the gradual release of said strap by one or more teeth at a time, said escapement ratchet mechanism including a first and a second hook mutually spaced by a non-integral multiple of the toothing pitch and capable of alternately engaging the toothing during controlled release of the strap, wherein said first hook of the escapement ratchet mechanism coincides with the main hook, and the second hook is structurally independent of the first hook, hinged on said base coaxially with the first hook and operationally connected to the first hook in order to disengage it from the toothing of the strap when the second hook is engaged therein and vice versa. 
     
     
       2. A device according to  claim 1 , wherein the operational connection between the first and the second hook comprises a support fixed to the second hook on the opposite side thereof with respect to the hinging axis, said support being engaged beneath the first hook, between this latter and the strap, in order to lift it in disengagement from the toothing when the second hook is pressed into engagement with the toothing. 
     
     
       3. A device according to  claim 2 , wherein said hooks each comprise a tubular hub for hinging to the base, said hubs being complementary in prolongation of each other to define a single hinging seat. 
     
     
       4. A device according to  claim 1 , wherein said hooks each comprise a tubular hub for hinging to the base, said hubs being complementary in prolongation of each other to define a single hinging seat. 
     
     
       5. A device according to  claim 1 , wherein resilient means are interposed between said hooks and the base, urging the first hook into engagement with the toothing of the strap and the second hook into disengagement from the toothing. 
     
     
       6. A device according to  claim 1  comprising a feed lever for advancing the strap with respect to the base, said feed lever being hinged at one end of a pair of connecting rods, the opposite end of which is hinged to the base. 
     
     
       7. A device according to  claim 6 , wherein the connecting rods of said pair are fixed to each other via a cross-member. 
     
     
       8. A device according to  claim 6 , wherein the first hook comprises an operating appendage extending partially alongside said lever. 
     
     
       9. A device according to  claim 8 , wherein said first hook comprises two operating appendages co-extending and mutually spaced, and said feed lever is at least partly contained between said appendages. 
     
     
       10. A device according to  claim 1 , wherein both said main and second hooks are equipped with operating appendages and respective retaining teeth arranged on the same side with respect to the hinging axis, such that the operational actuation for disengaging the hooks from the toothing of the strap includes in all cases the distancing of the corresponding operating appendages from the base.